The control of phytopathogenic fungi is of great economic importance since fungal growth on plants or on parts of plants inhibits production of root, stem, foliage, fruit or seed, and the overall quality of a cultivated crop. About 25 percent of all fungal diseases in agriculture and horticulture are caused by powdery mildew phytopathogens.
Because of the vast economic ramifications of fungal propagation in agricultural and horticultural cultivations, a broad spectrum of fungicidal and fungistatic products have been developed for general and specific applications.
Of background interest with respect to the present invention embodiments are fungicide compositions which contain an inorganic bicarbonate and an optional carbonate compound. It is known that bicarbonate and carbonate compounds exhibit fungicidal properties for agricultural purposes.
Phytopathology, 48, 169 (1931) by R. H. Marloth describes studies involving the physiology of fungi. The reference reports studies which demonstrate that sodium and potassium bicarbonate and carbonate salts are toxic to fungi such as Penicillium italicum and Penicillium digitatum.
U.S. Pat. No. 1,560,558 discloses the use of salts such as lithium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, potassium carbonate and ammonium bicarbonate as fungicide ingredients.
U.S. Pat. No. 4,599,233 describes a fungicide composition which consists of sodium bicarbonate in combination with a surface active food emulsifier such as sorbitan monostearate.
Japanese patent 53118523 describes the combination of sodium bicarbonate and lecithin as an active agent for the control of agricultural and fruit storage fungus diseases.
Japanese patent 56043207 describes a biocidal composition containing sodium bicarbonate and a polyglycerol fatty acid ester. The biocide controls Penicillium digitatum on oranges, Sphaerotheca fuligenea on cucumbers, Piricularia oryzae on rice, and mosaic virus on tomatoes.
Japanese patent 60097909 describes a soil fungicide prepared by admixing slaked lime with sodium bicarbonate, potassium bicarbonate, boric acid and phenolphthalein.
German patent DE 2927994 describes a fungicide which consists of sodium bicarbonate incorporated into a food-compatible surfactant such as saccharose laurate.
Japanese patent 57062208 describes horticultural fungicides in which the addition of sodium bicarbonate to polyoxin or thiophanatemethyl increases the fungicidal activity of the organic biocide against Botrytis cinerea on cucumbers.
Japanese patent 58023609 describes an agricultural fungicide composed of a mixture of sodium bicarbonate or potassium bicarbonate with cupric hydroxide, basic copper carbonate or basic copper sulfate. The combination of ingredients exhibits a synergistic fungicidal effect against cucumber early blight, tomato wilt, rice sheath blight, rice blast and citrus canker.
Of particular interest with respect to the present invention is the control of soilborne phytopathogenic fungi. Soilborne diseases are of significant economic importance to peanut industries in Oklahoma and other areas of the United States. These diseases include Sclerotinia blight (Sclerotinia minor Jagger), southern blight (Schlerotium rolfsii sacc.) and pod rot (Pythium myriotylum and Rhizoctonia solani Kuehn).
Fungicides are the common means of soilborne disease management in peanut crops. Because of increasing environmental and health related concerns, the use of organic pesticides is becoming increasingly tenuous, and there is substantial incentive to investigate the development of new fungicide products.
Ammonium bicarbonate has been applied by chemical spray application equipment to peanut field crops for control of Sclerotinia blight. Under the application conditions, the ammonium bicarbonate was phytotoxic, as evidenced by a reduction in peanut yield Peanut Science, 17, 28 (1990)!.
There is a continuing need for improved methods for providing preventive and curative fungicidal activity for the protection of cultivated plants with a minimum of phytotoxic side effects.
Accordingly, it is an object of this invention to provide a fungicide composition which can be applied effectively to cultivated plants, and which is within acceptable limits with respect to environmental and health concerns.
It is another object of this invention to provide a method of controlling fungi in cultivated field crops with a minimum of phytotoxic side effects.
It is a further object of this invention to provide a method for controlling soilborne Sclerotinia blight and other diseases in peanut crops by means of an ecologically safe inorganic fungicide with an acceptable degree of phytotoxic side effects.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.